Seismic Response Analysis Of Crossing-fault Tunnel

Generally, some serious damage may happen to the crossing-fault tunnel during earthquake. Based on conclusions of seismic damage phenomena and earthquake-resistant research status,the seismic behavior of crossing-fault tunnel is analyzed. Some conclusions have been achieved as follows:1)The non-linear behavior of long and big mountain tunnel are analyzed under some different conditions of fault movement.(a) Under the condition of different fault movement, during the same loading process,stress yielded first and yield scope is biggest under reverse fault condition, the damage extent is the second under the normal condition, and the smallest under the strike slip fault condition.(b) From the analysis of different rigidity of rocks, the results are showed as follows: With the fault movement, the tunnel lining is easier to be damaged under the condition of soft rock than under that of hard rock, compared the yield scope of the two conditions, that of the roof and side wall is bigger under soft rock condition than that under hard rock condition, and is similar at roof under the two conditions.(c) Different width of 5m, 20m, and 100m are studied to analyze the effect of different fault width to the tunnel lining under fault movement. With the bigger fault width, yield range of the bottom is increasing, but the high stress range in the active fault decreases, and both the high stress area and yield stress area at position of roof and side wall occur in the range of fault, and increasing with the increasing fault width. (d) Generally, the high stress area of tunnel lining is mainly from 90 meters in hanging wall to 50 meters in footwall around fault, which scope should be pay much more attention to in design.2) The porosity of concrete under different damage state is achieved by using different amount of air-entraining agent as concrete composion. The initial damage and peak damage of different concrete specimens with different porosity also can be got by tensile and compressive test. The relationship between porosity and damage of concrete can be showed by method of curve fitting. So the different damage state can be expressed by the porosity to describe concrete damage constitutive.3) A new damage model is got by improving Loland and Mazars damage model. Using concrete specimen of containing no air-entraining agent as initial damage state ,the relationship between stress and strain of compressive or tensile strength is achieved by concrete test. The concrete damage constitutive is deduced by the new damage model and relationship curve. 4) The concrete constitutive which is deduced by experimental results is embedded in the constitutive library MIDAS/GTS, and the correctness of the new constitutive model is proved by comparing simulating and testing phenomena.5) The behavior of crossing-fault tunnel under time-history loads is simulated, computed and analyzed by using damage constitutive model and MIDAS/GTS software.